Gun control system



F 1953 D. D. TERWILLIGER ET AL 2,628,535

GUN CONTROL SYSTEM 3 Sheets-Sheet 1 Filed NOV. 15, 1949 F 1953 D. D. TERWILLIGER EIAL 2,628,535

GUN CONTROL SYSTEM Filed Nov. 15, 1949 3 Sheets-Sheet 2 BY 455727? Adam/2505 F 1953 o. D, TERWILLIG ER ET AL 2,628,535

GUN CONTROL SYSTEM Filed Nov. 15, 1949 3 Sheets-Sheet 5 Patented Feb. 17, 1953 UNITED STATES ATENT OFFICE GUN CONTROL SYSTEM of Maryland Application November 15, 1949, Serial No. 127,382

14 Claims.

This invention relates to an improved gun control system for controlling the direction and sighting of a flexibly mounted gun.

An object of this invention is to provide a gun control system wherein a sighting station is provided remotely from the gun mounting, and in which the gun may be made to follow closely movements of the sighting means.

Another object is to provide, in such a control system, for operation of the sighting means, independently of the gun, with the latter remaining in stowed position until desired, but wherein, at any time desired, the gun may be quickly moved to a position corresponding to that of the sight.

A further object is to provide an improved structural interrupter for preventing interference between the structure adjacent the gun mount and the gun itself.

A further object is to provide such a structural interrupter wherein relatively small and light electrical elements perform the necessary interruption functions.

A further object is to provide a structural interrupter readily changeable to accommodate a particular mounting.

A further object is to provide a gun control system wherein the gun will automatically return to a fixed stowage position whenever it is released from control by its associated sighting Other and further objects will become apparent upon a reading of the following description and claims, especially when taken in view of the accompanying drawings.

In the drawings:

Figure l is a fragmentary perspective view of an armored vehicle provided with the gun control system of this invention;

Figure 2 is a fragmentary side view showing the arrangement of one of the gun turrets;

Figure 3 is a bottom plan View of said turret;

Figure 4 is a view looking forwardly at one of the sighting stations;

Figure 5 is a side view of the sighting station;

Figure 6 is a schematic diagram of the electrical control system; and

Figure 7 is a diagram of a portion of one of the switches shown in Figure 6.

Turning first to Figure 1, there is shown the upper portion of a military vehicle I provided with a pair of gun turrets 2, 3 and three sighting periscopes 4, 5 and 6. Just ahead of the left hand turret the upper surface of the vehicle is provided with a hatch I having a hatch cover 8 hinged thereto along its rear edge. Midway between the turrets a second hatch 9 is shown also having a cover it hinged thereto. Each of the turrets is provided with a gun II, l2, each turret being rotatable about its vertical axis to position its gun in azimuth, and each gun being mounted in its turret for swinging about a horizontal axis transverse of the gun for positioning the gun in elevation.

Figures 2 and 3 show the construction of one of the turrets, the other being substantially identical, except reversely arranged. The turret 2 includes a circular base plate I3 supported for rotation about its vertical axis by suitable antifriction bearings l4 carried by a stationary supporting ring l5 rigidly connected to the top plate i6 of the vehicle.

The plate i3 is provided with a generally rectangular, centrally located opening I! and along opposite sides of this opening are a pair of upstanding plates l8 of generally triangular shape. Pivotally supported between these plates I8 is a gun cradle assembly [9 of generally semi-cylindrical form, having trunnions 20 carried by suitable bearings 2| in the upper portion of plates l8. Gun II is rigidly carried by the cradle assembly, projecting outwardly as shown through the curved end wall thereof.

To elevate the gun about its transverse trunnion axis, a rotary hydraulic motor 22 is provided, which, through suitable gearing (not shown) within the housing 23, drives a pinion 24 meshing with an arcuate rack 25 on one side wall of the cradle assembly.

To rotate the gun and turret about the vertical turret axis, a second rotary hydraulic motor 26 is provided, which, through suitable gearing (not shown) within the housing 21, drives a pinion 28 meshing with a ring gear 29 formed on the supporting ring [5.

Motors 22 and 26 are adapted to be rotated in either direction and at any desired speed, and may be operated individually or simultaneously as the circumstances demand. Hydraulic fluid is supplied to the motors by an electrically controlled hydraulic transmission unit 30 carried, as shown, on the turret between the housings 23 and 21.

This transmission unit 30 is of the type well known in the art and no detailed description is deemed necessary. Sufiice it to say that the unit is arranged to control the direction and rate of flow of hydraulic fluid to either motor in substans tially direct proportion to the phase relationship and potential of a control voltage applied thereto. The control voltage for controlling fluid flow to the turret rotating motor 26 is obtained from the azimuth servo-amplifier 3| shown in the electrical diagram, Figure 6. That for controlling fluid flow to the gun elevating motor 22 is obtained from the elevation servo-amplifier 32 also shown in the electrical diagram.

Electrical connections between the turret and the associated control and generating apparatus carried within the vehicle include a slip ring assembly 33 arranged below and coaxial with the turret. The slip ring assembly includes an inner contact ring assembly 34 rigidly supported from the turret by suitable bracket arms 35 and 3?. The slip ring assembly further includes an outer brush holder 38 having brushes (not shown) therein for electrically contacting the individual contact rings of assembly 34. Holder 38 is fixedly supported from the interior of the vehicle by a bracket arm 39. The various electrical leads to the brushes may be housed within this arm 39 while those to the slip rings may be housed within arm 31.

Figures 4 and show, somewhat diagrammatically, one of the periscope sighting and control stations. The periscope 5 is arranged to project upwardly through the top wall 5 of the vehicle and is of the known type wherein the eyepiece 4| remains stationary as the optical system rotates to vary the line of sight. A pair of hand grips 42' is mounted from the periscope drive and control housing 43 so that they may be moved about a vertical axis 44 to energize the periscope azimuth drive motor 45 to shift the line of sight in azimuth, and may be rocked about horizontal axis 46' to energize the periscope elevation drive motor 41 to shift the line of sight in elevation. The details of thi sight control system are quite conventional and well known in the gun control art and form no part of the present invention.

A selsyn system is provided for causing the gun to follow the movements of the particular sight then in control thereof. Mounted on the sight drive housing 43 are fourselsyn generators 48, 49, 50 and 5|. selsyn 48 has it rotor geared to the sight elevating mechanism so that it rotates at a rate 27 times as fast as. the sight elevates. Selsyn 49 is also geared to the sight elevating mechanism, but at a 1:1 ratio. selsyns 50 and 5,1 are similarly geared to the sight rotating mechanism at, 27:1 and 1:1 ratios, respec-.

tively.

Mounted on the gun elevation drive housing 23 are a pair of selsyns 52 and 53 having their rotors. geared to the gun elevating mechanism in 21:1 and 1:1 ratios, respectively, and on the turret rotating drive housing 2 1, a pair of selsyns 54 and 55 are mounted, also driven in 27:1 and 1:1 ratio with the turret. The various related pairs of selsyns are electrically connected through a master selector switch 40, as shown in Figure 6, so that whenever the gun is out of step with its sight, in elevation, for example, control voltages of phase and magnitude corresponding to the relative direction and amount of mis-alignment will appear at the output terminals 58 and 51 of the selsyns 54 and 55. Normally the control voltage from the 2.711 selsyns will be applied to the elevation and azimuth servo-amplifiers to cause the latter to so control the transmission as to actuate the elevation and azimuth motors 22 and 23 in such a direction and at such a speed a to correct the mis-alignment.

If, however, the mis-alignment exceeds some predetermined amount, means i provided for switching the control to the 1:1 selsyn system to insure against losing control of the gun. At the same time the gun firing circuit'is made inoperative. To obtain these results, a sensitive error-detecting relay 58 is connected to the control voltage output terminal 51 of the 1:1 selsyn 55,, and is adapted to be energized whenever this voltage reaches a value corresponding to an error of the predetermined magnitude. Energization of relay: 58 causes energization of selsyn selector relay 59 which breaks the control connection 59a between the 27:1 selsyn 54 and the elevation servo-amplifier 32 and makes connection between the 1:1 selsyn 55 and the servo-amplifier. At the same time contacts 59b on relay 59 open the circuit to firing control relay 60, preventing operation of the firing solenoid 6| until such time as control is returned to the 27:1 selsyn system.

A similar error-detecting relay 62 and selsyn selector relay 53 are provided in the azimuth control system for the same purposes.

Turrets 2 and 3 are adapted to be controlled, either individually or collectively from any of the periscope sighting stations. Master switch 45, as shown in Figures 6 and '7, is provided to select which of the control and sighting stations is to control which turret. No attempt is made to show this switch in detail in Figure 6 since it would unnecessarily complicate the wiring diagram. Suffice it to say that the switch comprises a plurality of 6-position, single-pole section adapted to be actuated simultaneously. Two sections, one for each turret, are used for each of the control circuits. Thus the uppermost portion of switch 45 shown in Figure 6 would actually comprise two sections 64 and 55 connected to the sighting stations and to the turret as shown in Figure '7. With the switch arms 66 and 57 set as shown in Figure 7 the. left hand turret 3 would be under the control of the left hand periscope sighting station 6 while the right hand, turret 2 would be under the control of the right hand sighting station 5. This is the switch position assumed in Figure 6', wherein only those. switch sections and contacts actually used to con-. nect the left hand turret 3 to the left hand periscope station 6 havebeen illustrated.

Note that, if the switch arms 55 and 5,1 are moved to the position wherein they engage with contacts 68 and 69 respectively the control of left hand gun 3 will be switched to the commander's sighting station 41 while gun 2 will remain under the control of the right hand sighting station 5. If the switch arms are moved to contacts 15 and T l the control of both guns will be from the comand-ers sighting station, etc.

Each of the grips on the sighting device is provided with an acquisition switch I2 and a trigger switch 13. Adjacent the master switch 45 at the master control station are provided a Scan-Track switch 14 and a Safe-Fire switch 15 for each turret.

As shown in Figure 6, acquisition switch 12 and Scan-Tract switch 14 are arranged in series relation to control a pair of stowage relays i6 and "H. Stowage relays 16 and H are adapted, when deenergized (as shown in Figure 6) to disconnect the sight and turret selsyns from one another so that actuation of the sight will not cause movement of the gun. Moreover in this deenergized condition, the stowage relays 15 and 71 apply an A.-C. potential of fixed value v.) to two of the stator windings of the turret selsyns. Under these conditions there will be a single, definite position of each of the turret selysn rotors where no voltage will appear at its output terminal. The turret selsyns are so oriented with the turret drive mechanism that these positions of the various rotors correspond to the desired stowage position of the gun shown in Figure l for example. Thus, whenever the operator releases the acquisition switch 12 or the commander throws the switch 14 from Track to Scan, the gun will automatically and quickly return from whatever position it may be in at the time, to its stowed position.

If, while scanning, the operator sights a target (assuming that switch H is in Track position) he need merely press switch 64 to energize relays 16 and Ti to restore the selsyn circuits between the sight and the turret, whereupon the gun will quickly swing into step with the sight. This arrangement is especially desirable as it permits continuous scanning without requiring the relatively large drain on the electrical system that is involved when the turret is being operated. Yet at the more pressing of a switch, the gun will swing to the desired firing position.

Trigger switch 13 and Safe-Fire switch are connected in series relation between acquisition switch 12 and the firing solenoid 6!, so that the gun can be fired only when all three switches are closed at the same time.

As is obvious from Figure l, the minimum elevation angle at which either gun may be safely fired will vary with its position in azimuth, and a so will be affected by the position of other movable structure on the vehicle. For example, with hatch cover 8 closed, the gun [2, when directed forwardly, can be depressed below the horizontal position and still clear the vehicle, while with the hatch cover open, the gun cannot be lowered even to the horizontal position without interference. Ther is, therefore, for each sector of space about a turret, a particular limiting clearance angle below which the gun may not be safely fired, and, if there is movable structure within a particular zone, another limiting angle, at times effective, depending on the position of the movable structure.

A structural interrupter system is therefore inconporated in the control system to automatically prevent lowering of a gun to a position which might cause interference. The interrupter of this invention operates electrically and includes a commutator assembly including a plurality of comutator rings l8, l9 and 88 suitably attached to and insulated from the under side of the stationary supporting ring I5 as shown in Figures 2 and 3. Each commutator ring is formed from a plurality of commutator segments, insulated from one another, and each corresponding to a particular zone of space about the turret. The space may be thus divided into as many zones as is deemed desirable; obviously the more segments that are employed, the more closely can the guns be made to follow the structural profile of the vehicle. To avoid unnecessary confusion, however, each commutator ring is shown in the drawing as being formed of but three segments 78A, 13B, 58C, etc, dividing the space about the turret into a forward zone, a gun-to-gun zone (wherein the gun of one turret is aimed generally across the vehicle and over the other turret) and a remaining zone, to the rear and adjacent side of the vehicle.

Carried by the base plate l3 of the turret is a brush holder 81 carrying a contact brush 82, adapted to contact the inner commutator rin 78, and a brush 83 adapted to bridge across commutator rings 79 and 86 as clearly shown in Figure 2. Suitable springs, not shown, bias the brushes into continuous contact with the associated rings.

Turning to Figure 6, th commutator segments 18A, 18B, 180, etc. for turret 3 are shown associated with the remaining elements of the interrupter system for that turret.

The corresponding segments for the other turret are also shown, being identified by similar numbers primed.

The commutator system is basically a resistance bridge network, so arranged that whenever the gun starts to move below a critical angle for any particular sector, the bridge will be thrown out of balance in such a sense as to energize an interrupter relay, which, in turn will remove the gun elevating mechanism from control by the sight and apply a voltage of proper phase to make the gun immediately move upwardly into a safe firing position. More specifically, the bridge network includes a potentiometer 84, mounted on and geared to the gun elevating mechanism (see Figures 2 and 3), so that its movable contact will move in synchronism with the gun. This potentiometer is connected directly between the 28 v. D. C. line and ground so that the potential of its movable contact 85 will always correspond to the angular position of the gun in elevation.

Also connected between the 28 v. D. C. line and ground is a plurality of tapped resistors 88, 57, 83, 29, the number of which will vary with the number of zones and the number of difierent limiting angles desired for a particular installation. The taps from these resistors are electrically connected to the various commutator segments as shown in Figure 0. Connected between brush 82 and movable contact 85 of the elevation potentiometer is an interrupter relay 9G, in series with a rectifier 9i so polarized that whenever the potential of brush 82 is greater than that of contact 85, interrupter relay 9% will be energized. The tap on resistor 86 is so positioned that its potential corresponds to the minimum elevation angle for the gun to clear all structure within the rear and side zone corresponding to segment 186.

Thus with the gun positioned in this particular zone, as long as the gun is aimed above this minimum clearance angle, relay 98 will be deenergized, but as soon as the gun is moved to a position below this clearance angle, the relay will be energized to open the normal elevation control circuit at 92 and to connect the elevation servoamplifier to an A.-C. voltage of pro-per phase and magnitude to cause the servo-amplifier to control the gun elevating mechanism to elevate the gun.

Where movable structure on the vehicle is located within a particular zone, automatic selection of two or more different clearance angles may be desired, depending upon the position of the movable structure at that particular time.

Thus when the gun is aimed across the vehicle, not only must safe gun fire clearance be provided, but physical interference with the other turret or gun must also be avoided. The latter problem is most severe when both guns are aimed across the vehicle, or in other words, when both guns are in their gunto-gun sectors corresponding to segments B, B of their commutators. iapped resistor 81 is connected to segment 183 to act, just as does resistor 86, to determine the limiting fire clearance angle for gun 12 of turret 3, while in its gun-to-gun sector, at all times except when the other gun H is also in its gun-to-gun zone. When this latter condition prevails, a higher clearance angle is obviously necessary and the following apparatus is provided to apply a correspondingly higher voltage to segment 1813.

As shown in Figure 6, the gun-to-gun segment 8% for turret 2 is electrically connected to segment 13B of turret 3. connected to a relatively highv potential tap on resistor 88. Thus whenever turret 2 Min its gunto-gun zone its brush 83' will bridge contacts 79B and 8.63 and the potential of segment 1813 will be raised to some value intermediate that corresponding to the taps on resistors 87 and 88. Thus brush 82 will be at a higher potential than if. turret 2 were in some other zone, and the interrupter relay 9% will be energized at a correspondingly higher elevation angle of the gun.

When the gun is in its forward zone its safe clearance angle will vary with the position of hatch cover 8. In this case a hatch switch 93 is provided, being arranged for actuation by the hatch cover, for energizing r deenergizing a hatchrelay 94, which in turn selects which of two taps on resistor 89 will be electrically connected to front segment 18A. When the hatch cover is shut, the switch 93 will be open and the relay 94 will he deenergized as shown in Figure 6 so that the low-voltage tap corresponding to a low clearance angle of the gun will be efiective. When the hatch cover is opened, relay 94 will be energized, switching its contacts 95 to the high voltage tap on resistor 89, corresponding to a higher clearance angle.

Operation While the operation of the above described Control System is believed to be fairly obvious, typical operation under certain assumed conditions may be as follows:

For example, assume that the armored vehicle is traveling along with no enemy target in sight, any or all of the periscope sighting stations will be available for scanning purposes, while the guns will be in their stowed position. Under such conditions, the Track-Scan switches, for the two turrets will be set in their Scan positions. enemy is sighted, say to the left of the vehicle, the commander will set the selector switch it to whatever position appears desirable for most effective counter actionin this case, probably to the position giving the left hand sighting station 6 control over both guns. He will also set the Track-Scan switches for both turrets to their Track position. The operator of the left hand sighting station may then, by appropriate manipulation of his control grips, follow the movements of the target and, as it approaches firing range, will depress the acquisition switch on the control grips. This will energize the stowage relays i6 and 77 for both guns, and the guns will quickly swing into a position corresponding to the line of sight of the periscope and will thereafter continue to track with the sight. Firing of both guns may be obtained by merely pressing the trigger switch on the grips whenever the operator deems it desirable.

Meanwhile, the right hand gunner, and possi-bly the commander, will continue to operate their sighting periscopes to scan about the vehicle. If another enemy is sighted in a different zone, the commander will set the selector Segment 79B isv If an lid switch 40 to the position giving himself, or the right hand gunner, control over the right hand turret, while leaving the left hand gun under the control of the left hand gunner. Under these conditions each gun will track its respective sighting station entirely independently of the other.

If the target for a. particular turret moves into a position wherein the gun could not be safely fired without danger of striking part of the vehiclev structure, the interrupter relay for that particular turret will be energized as previously described to maintain the gun above the critical elevation angle for that particular zone. The operator, however, may continue to follow the target both in azimuth and elevation with his sight. However. as soon as the sight is depressed below the critical angle, a misalignment between the gun and the sight will obtain, causing a voltage of sufiicient potential to appear at the output of the 1:1 elevation selsyn 55, for that particular gun, to energize the elevation error-detecting relay 58. Relay 58 in turn will energize the selsyn selector relay 59 to open the firing circuit for that gun and to switch control from the 27:1 to the 1:1 selsyn system to prevent losing control of the gun in elevation. However the gun will remain under the control of the 27:1 azimuth selsyn system and will therefore continue to follow the movements of the sight in azimuth. As soon as the target has moved to a, position wherein it is again above the critical angle, the gun will again swing into alignment with the sight and the error-detecting relay 58 will drop out, restoring control of the gun to the 27:1 system and again permitting firing of the gun.

In the event that the ammunition supply is exhausted for either gun, the operator need merely release the acquisition switch which will in turn deenergize the stowage relays, and the gun will immediately swing to stowage position wherein it can be readily serviced. The operator meanwhile can continue to track the target and as soon as the gun is reloaded will have merely to again press the acquisition switch to cause the gun to once more swing into line with the sight.

While in the disclosed device but three segments were shown in each commutator ring, it is obvious that any number of segments could be employed, depending upon how closely it was desired that the interrupter pattern follow the contour of the vehicle. Obviously, also, vacuum or gas trigger tubes could be used in place of certain of the relays, they being well known equivalents.

While the vehicle is shown as being provided with but three sighting stations and two turrets, the principles involved are clearly applicable to anti; desired number of sighting stations or turre Many other modifications could obviously be made without departing from the spirit and scope of the appended claims.

We claim as our invention:

1. A gun control system for a vehicle having a turret mounted thereon for rotation in azimuth about a generally vertical axis and a gun pivotally carried by said turret for angular adjustment in elevation, power means for rotating said turret and for swinging said gun in elevation whereby said gun has a field of fire coverage over a predetermined sector of space about said turret, control means normally controlling the operation of said power means for pointing said gun in any desired direction within said sector, said vehicle including structure normally projecting into said field of five coverage, means for efiectively dividing the space about said turret axis into individual zones and comprising a commutator assembly including a plurality of commutator segments corresponding to said zones and contact means movable relative to said commutator segments in accordance with movement of said turret about its axis and adapted to electrically contact said individual segments, a source of electrical potential, means connecting each of said segments to said source whereby to apply a voltage to each segment proportional to the minimum angular position of elevation of said gun necessary to clear such of said structure as lies within the zone cor responding to that particular segment, means operatively connected to said gun and to said source and having a voltage output terminal the potential of which varies in accordance with the angle of elevation of said gun and means connected to said contact means and to said output terminal and responsive to a predetermined difference in potential therebetween to cause said control means to be made inefiective to cause movement of said gun beyond said clearance angle.

2. A gun control system for a vehicle having a turret mounted thereon for rotation in azimuth about a generally vertical axis and a gun pivotally carried by said turret for angular adjustment in elevation, power means for rotating said turret and for swinging said gun in elevation whereby said gun has a field of fire coverage over a predetermined sector of space about said turret, control means normally controlling the operation of said power means for pointing said gun in any desired direction within said sector, said vehicle including structure normally projecting into said field of fire coverage, means for effectively dividing the space about said turret axis into individual zones and comprising a commutator assembly including a plurality of commutator segments corresponding to said zones and contact means movable relative to said commutator segments in accordance with movement of said turret about its axis and adapted to electrically contact said individual segments, a source of electrical potential, means connecting each of said segments to said source whereby to apply a voltage to each segment proportional to the minimum angular position of elevation of said gun necessary to clear such of said structure as lies within the zone corresponding to that particular segment, means operatively connected to said gun. and to said source and having a voltage output terminal the potential of which varies in accordance with the angle of elevation of said gun, and means connected to said contact means and to said output terminal and responsive to a predetermined difference in potential therebetween to cause said control means to be made ineffective to cause movement of said gun beyond said clearance angle, certain of said structure being movable relative to said vehicle between positions requiring diiferent clearance angles, and means responsive to movement of said certain structure to said different positions to cause correspondin changes in the potential applied to the segment corresponding to that zone within which said certain structure lies.

3. A gun control system for a gun mounted for angular adjustment about substantially perpendicularly related axes, power means for swinging said gun about said axes whereby said gun has a field of fire coverage over a predetermined sector of space about said gun, control means normally controlling the operation of said power means for pointing said gun in any desired direction within said sector, structure normally projecting into said field of fire coverage, means for effectively dividing the space about said gun into individual zones and comprising a commutator assembly carried by the unit and including a plurality of commutator segments corresponding to said zones and contact means movable relative to said segments in accordance with movement of said gun about a first of said axes and adapted to electrically contact said individual segments, a source oi eiectrical potential, means connecting each of said segments to said source whereby to apply a voltage to each segment proportional to the minimum angular position of said gun about the other of said axes necessary to clear such of structure as lies within the zone corresponding to that particular segment, means operatively connected to said gun and to said source and having a voltage output terminal the potential of which varies in accordance with the angular posi tion of said gun about said other axis, and means connected to said contact means and to said output terminal and responsive to the difference in potential therebetween to render said control means ineffective to cause movement of said gun to an angular position about said second axis less than said minimum clearance angle.

4, A gun control system for a gun mounted for angular adjustment about substantially perpendicularly related axes, power means for swinging said gun about said axes whereby said gun has a field of fire coverage over a predetermined sector of space about said gun, control means normally controlling the operation of said power means for pointing said gun in any desired direction within said sector, structure normally projecting into said field of fire coverage, zoning means effectively dividing the space about said first axis into zones and responsive to the position of said gun in a particular zone to produce an output voltage substantially proportional to the minimum angular position of said gun about the second of said axes necessary to clear such of said structure as lies within that particular zone, gun position means connected to said gun and adapted to produce an output voltage proportional to the angular position of said gun about said second axis, and means connected to said zoning means and to said gun position means and responsive to the difierence in potential between said output voltages to render said normal control means ineffective to cause movement of said gun. below said clearance angle.

5. A gun control system for a gun mounted for angular adjustment about substantially perpendicularly related axes, power means for swinging said gun about said axes whereby said gun has a field of fire coverage over a predetermined sector of space about said gun, control means normally controlling the operation of said power means for pointing said gun in any desired direction within 1 said sector, structure normally projecting into said field of fire coverage, zoning means effectively dividing the space about said first axis into zones and responsive to the position of said gun in a particular zone to produce an output voltage substantially proportional to the minimum angular position of said gun about the second of said axes necessary to clear such of said structure as lies within that particular zone, gun position means connected to said gun and adapted to produce an output voltage proportional to the angu- 'lar position of said gun about said second taxis, .andmeans connected :to said zoning means and "to said gun position .meansand responsive to the difference in potential between said output voltages to render said normal control :means ineffective to cause movement of said gun below .said clearance angle, certain of said structure being movable relative to said gun between positions requiring different clearance angles, and means responsive to movement of said certain structure to said difierent positions to cause corresponding changes in the output voltage of said zoning means for that ,zone within Whichsaid certain structure lies.

6.. A gun controlsystem for a gun-mounted for pivotal movement about perpendicularly related axes, power means for swinging said gun about said axes, control means normally controlling said power means for pointing :said gun in any desired direction about said axes, means responsi ve to the position of said gun about a first of said axes for producing an output voltage substantially proportional to a desired clearance angle of said gun about the second of said axes, means responsive to the angular position of said gun about said second axis s-ior producing an output voltage substantially proportional to the angular position of the gun about said second axis, and interrupter means responsive to said output voltages for rendering said normal i091]- trol meansineffective to control movement of said gun about said second axis whenever a predetermined one of said output voltages exceeds the other.

'7. A-gun control system for a gun mounted for pivotal movement about perpendicularly related a-xes, power means for swinging said gun about said axes, control means normally controlling saidpower means for pointing saidgunin any desired direction about said axes, means responsive to the position of said gun about a first of said axes for producing an output voltage substantially proportional to .a desired clearance angle of said gun about the second of said axes, means responsive to the angular :position of :saidgun about said second axis for producing an out-put'voltage substantially proportional to the angular position of the gun about said second axis, interrupter means responsive to said output voltages for rendering said normal control means ineffective to control movement of said gun about said second axis whenever a predetermined one of said output voltages exceeds the other, and means responsive to operation of said interrupter :means for causing said power means to move said gun about said second axis to a position wherein said output voltages are substantially. equal.

;8. In a gun control system for a gun mounted V for movement about an axis, control means for said gun including a sighting mechanism having means for shifting the line of sightabout a corresponding axis, means for causing said gun to follow movements of said sighting mechanism includin la plurality of sets of :selsyn mechanisms, each set including a pair of interconnected selsyns, having their rotors connected to said sighting mechanism and said gun respectively for movement at a predetermined 'low ratio relative thereto, and a second pair of interconnected selsyns having their rotors connected to the sighting mechanism and to the gun respectively for movement at a predetermined higher :ratio relative thereto, servo-means normally responsive to the voltage across the rotor of said high-ratio gun selsyn for controlling movement of said gun,

selector 2111622113 responsive to a predetermined voltage across the rotor :of said loweratio gun selsyn for switching control of said servo-means :irom saidhigh-iratio to said low-:ratio :gun ZSBISYII, means for causing firing :of said gun :and :means responsive to such actuation of :said selector means ,for rendering inoperative said .firin means.

9. .Inagun control system :forlag un mounted for pivotal movement about :anaxis, :control means for said gun including sighting :means having means for shifting the line of sight about a corresponding axis, means foricausing said :gun to follow movements of zsaidisighting :means inelu high-ratio and low-ratio selsyn systems interconnecting said sighting meansand-said gun, and servo -mechan'ism normally responsive to the output of said high-ratio :se'lsyn system for controlling movement of said gun, 'means responsive to a predetermined angular misalignment between said line of sight and said gun for switching control :of said servo-mechanism from said high-ratio to said low-ratio 'sels yn-system, means for firing said gun, and fire interrupting means responsive to operation of said switching means for'rendering inoperative said firing means.

10. 'In a gun control system for a gun mounted for pivotal 'movement about an axis, control means for said gun, power means for moving said gun, a selsynsystem normally responsive to said control means and connectingsaid control means to said power means, said power means being normally responsive to the output voltage of said se'lsyn system to cause said gun :to :follow the movements of said control means, a switch, and means responsive to actuation of said switch for breaking the connection between said power means and saidzcon-trol means through saidselsyn system and for applying a predetermined voltage to said power means, whereby said gun moving means will cause said gun 'to move to a predetermined stowage position corresponding to said predetermined output voltage.

11. A gun control system for a gun mounted for pivotal movement about perpendicularly related axes, power means for swinging said gun about said axes, control means normally controlling said power means for pointing said gun in any desired direction about said axes, means responsive to the position of said gun about :a

first of said axes for producing an output voltage substantially proportional to a desired clearance angle of said gun about the secondoi said axes, means responsive to the angular position of said gun about said second axis for producing an out put voltage substantially proportional to the angular position of the gun aboutsaid second axis, and interrupter means responsive to said output voltages for 'rendering said normal control means ineffective to control movement of said gun about said second axis whenever a predetermined one of said output voltage exceeds the other, said normal control means including a sighting mechanism having means for shiftin the line of sight about corresponding axes, means for causing firing of said gun, and means responsive to operation of said sighting mechanism to shift the line of sight a predetermined amount beyond said clearance angle for rendering said firi-llg'meansinoperative.

.12. A gun control system for a gun mounted for movement about perpendicularly related axes comprising, sighting mechanism including means for shifting the line of sight about corresponding axes, control :means responsive to said sighting mechanism for normally causing said gun to follow movements of said sighting mechanism, means for rendering said control means ineffective to cause movement of said gun about either axis whereby said sight may be operated independently of the gun, structural interrupter means responsive to movement of the gun about one of said axes beyond a predetermined angle for also making said control means ineffective to cause movement of said gun about said one axis while retaining control of said gun about the other axis, means for causing firing of said guns, and means responsive to a predetermined degree of misalignment between said sighting means and said gun for rendering said firing means inoperative.

13. In combination with a vehicle, a turret mounted for rotation in azimuth about a generally vertical axis, a gun pivotally carried by said turret fOr angular adjustment in elevation, power means for rotating said turret and for swinging said gun in elevation whereby said gun has a field of fire coverage over a predetermined sector of space about said turret, control means normally controlling the operation of said power means for pointing said gun in any desired direction within said sector, said vehicle including structure normally projecting into said field of fire coverage, means for dividing said sector into zones including a commutator ring comprising a plurality of segments each corresponding to a zone of said sector, contact means rotatable with said turret, and means controlled by said segments and said contact means for making said control means inoperative to cause depression of said gun below a predetermined angle for any particular segment.

14. In combination with a vehicle, a turret mounted for rotation in azimuth about a generally vertical axis, a gun pivotally carried by said turret for angular adjustment in elevation, power means for rotating said turret and for swinging said gun in elevation whereby said gun has a field of fire coverage over a predetermined sector of space about said turret, control means normally controlling the operation of said power means for pointing said gun in any desired direction within said sector, said vehicle including structure normally projecting into said field of fire coverage, means for dividing said sector into zones including a commutator ring comprising a plurality of segments each corresponding to a zone of said sector, contact means rotatable with said turret, a source of voltage of predetermined potential connected to each individual segment, elevationresponsive means connected to the gun for producing a second voltage having a potential which varies in generally direct relation to the elevation of the gun, and means connected between said contact means and said elevation-responsive means and responsive to said voltages to limit further movement of the gun in one direction Whenever a predetermined one of said voltages exceeds the other.

DAVID D. TERWILLIGER.

HARRY MAZUR.

LESTER L. JACKSON, Jn.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,408,070 Hull et al Sept, 24, 1946 2,415,967 Pontius Feb. 18, 1947 FOREIGN PATENTS Number Country Date 609,306 Great Britain Sept. 29, 1948 

